Common Reptile Diagnostics Flashcards
What would be the safe volume of blood to take from the following reptiles?
- Nagini, 3 y/o FI, 60 g
- Lizzie, 6 y/o FI, 2 kg
total safe amount is 1% of BW in grams
- .01 x 60g = 0.6 mL
- .01 x 200g = 20 mL
What are the preferred blood collection sites for chelonians, snakes, lizards, and crocodilians?
CHELONIANS - subcarapacial sinus, jugular, coccygeal, brachial plexus
SNAKES - cardiocentesis, palatine, ventral coccygeal
LIZARDS - ventral coccygeal, ventral abdominal, jugular
CROCODILIANS - post-occipital sinus, coccygeal;
What should be done once blood is successfully obtained from a reptile? What is the anticoagulant of choice?
blood smear
heparin
What 2 erythrocyte parameters are for reptile bloodwork?
- PCV - 20-45%, within (heparinized) microhematocrit tubes
- RBC - reptile automated cell counter, manual hemocytometer + staining/dilution
What are the main 2 options for staining/diluting RBCs for manual counting on a hemocytometer?
- Eopette/Leukopette (Phloxine B) - only stains granulocytes
- Natt-Herricks solution - can differentiate RBCs (small lymphocyte) and WBCs (thrombocyte)
Hemocytometer:
What is the normal morphology of reptile RBCs? How do immature ones compare to mature ones?
oval with an irregularly marginated nucleus
immature RBCs are smaller, rounder, and have basophilic stippling
What are 3 locations that new RBCs are produced in reptiles?
- BM
- extramedullary = liver, spleen
- mature circulating cells divide and form daughter cells (will have mitotic figures)
How can reticulocytes be observed on a blood smear? How much of the RBC should they take?
new methylene blue
2.5% or less
How are WBCs measured in reptiles?
different morphologies compared to mammals and cannot use an automated counter —> manual counts on blood smears stained with Romanowski or Wright-Giesma
RBCs and WBCs:
- large arrowhead = lymphocyte
- asterisk = thrombocyte
- arrow = azurophil
What is the most common granulocyte in reptiles? What are the 2 major aspects of its morphology?
heterophil - analogous to neutrophils
- round, clear cytoplasm
- eosinophilic, elongated/spindle-shaped granules
What are 4 indications of toxic heterophils? What does this mean?
- basophilic cytoplasm
- abnormal granules
- vacuoles
- degranulation
a way to monitor chronic disease processes
What are the 2 major morphological aspects of eosinophils? What species lack them?
- similar in size and shape to heterophils with an eccentric nucleus
- spherical (red) granules —> “gumballs”
What WBC is seen in this blood smear?
green iguana eosinophil
What are the 2 major morphological aspects of basophils? What must they be differentiated from?
- smaller
- darkly basophilic granules obscure central, nonlobed nucleus
toxic heterophils
What are the 5 major morphological aspects of lymphocytes?
- lack granules
- high nucleus:cytoplasm ratio
- basophilic cytoplasm
- phagocytosed particles or RBCs can be seen in cytoplasm
- contour to surrounding cells
What do reactive lymphocytes indicate? What is their morphology like?
antigenic stimulation
- basophilic cytoplasm
- contain discrete punctate vacuoles
What is the morphology of monocytes like?
largest leukocyte with variably shaped contour and nucleus
What is a common variation of monocytes in reptiles? How do they compare in species?
azurophils
- non-squamates = normal variation of monocytes containing azurophilic granules
- snakes = distinct cell type that function similarly to neutrophils and contain fine granules and round nuclei
Label the cells seen in this blood smear.
- arrow with long arrowhead = monocyte/azurophil
- normal arrow = heterophil
- large arrowhead = lymphocyte (low cytoplasm!)
- skinny arrow with large arrowhead = eosinophil
- asterisks = RBC
Label the cells seen in this blood smear from a snake.
- large arrowhead = lymphocyte (low cytoplasm!)
- asterisk = thrombocyte
- normal arrow = azurophil (darker, large cytoplasm, small nucleus)
What are the 3 major morphologic aspects of thrombocytes?
- small, oval basophilic cells
- central basophilic nucleus
- pale-blue or colorless cytoplasm
(*)
Label the cells seen in this blood smear.
- arrowhead = eosinophil
- long arrow with large arrowhead = monocyte (large cell!)
- 2 normal arrows = heterophils
- asterisks = thrombocytes
What can indicate a left shift on blood smears? Infection?
presence of myelocytes and metamyelocytes in circulation
intracellular bacteria within WBCs
What are some factors that affect the normal reptile hemogram?
- species
- slide staining and evaluation technique
- health status
- nutritional status
- age
- reproductive status
- stress level
- gender
- venipuncture site
- season
- hibernation status
- captivity status
- environmental factors
What is considered anemic in reptiles? What is indicative of regeneration? How does this compare to mammals/birds?
PCV < 15%
polychromasia
RBCs are much longer lived in reptiles (600-800 days), therefore response of regeneration is muted
What are some common causes of chronic anemia? Acute?
CHRONIC - infectious/infestations, improper husbandry and nutrition, toxicity, chronic organ failure, neoplasia
ACUTE - blood loss
What is a common cause of anemia in reptiles due to collection methods?
lymph contamination —> hemodilution
- decreased PCV and increased lymphocytes with no evidence of regeneration
What is considered polycythemic in reptiles? What is the most common cause?
PCV > 40%
dehydration —> increased PCV and TP (common cause of kidney failure in chameleons)
What are 3 causes of inclusions seen in RBCs on blood smears?
- artifact from staining
- viral particles
- hemoparasites - Hepatozoon, Plasmodium (commonly subclinical)
Why is infection commonly challenging to diagnose in reptiles?
single leukogram is not indicative of chronic diseases commonly affecting reptiles
- long term monitoring of blood work recommended
What is the prefered method of interpreting WBC in reptiles when diagnosing infections in reptiles?
follow the WBCs over time rather than a single point sample —> more important to interpret differential and leukocyte morphology
What are 4 common causes of leukocytosis?
- inflammation/immune response
- infection
- stress
- neoplastic leukemia - snakes, lizards
What are common causes of leukopenia in reptiles?
- increased loss or destruction
- decreased production
- prolonged Fenbendazole use
What is the most common cause of abnormal biochemistry values in reptiles? What is used for these panels?
lymph contamination —> reduces all values, especially TP and K
use of panels/rotors specific for reptiles/avian species
What makes up the TP value? How is it interpreted?
albumin + globulins + fibrinogen fractions
compare ALB to GLOB
Where is albumin produced? What is its purpose?
liver
maintain oncotic pressure
What are common causes of increased and decreased albumin?
INCREASED - dehydration, reproductively acitve female (yolk formation!)
DECREASED - reduced intake of amino acids, reduced production due to liver disease, increased loss from GIT and kidneys (+ burns)
What produces globulins? What offers the most detailed summary?
immune system
commonly calculated on normal panels, but gel electrophoresis differentiates albumin from alpha, beta, and gamma globulins
What are the most common causes of increased and decreased globulins?
INCREASED - inflammation (gamma = chronic)
DECREASED - rare
What are the 4 major liver parameters included in reptile biochemistry panels?
- ALT - liver, kidneys, other tissues
- ALKP - liver, kidneys, intestines, bone
- AST - fairly sensitive for liver disease + kidney, muscle
- bile acids - more reliable indicator of hepatic function
What are some liver parameters not as commonly included in reptile panels?
- GGT - little to no activity in most tissues
- LDK - fairly nonspecific, liver, kidneys, other tissues
- GDH - liver
- biliverdin - product of RBC breakdown, lack biliverdin reductase = no bilirubin
What is a more common renal parameter included in reptile panels? What is the more important reference for kidney disease?
uric acid —> produced by liver, carnivore > herbivore
Ca:P (2:1) - <1 = renal disease
What are causes of increased and decreased uric acid in reptiles?
INCREASE - dehydration, acute renal failure, postprandial —> causes gout!
DECREASE - hepatic disease
How do reptiles metabolize sodium? What are common causes of increases and decreases?
cation present in the extracellular fluid —> ingested in the diet and excreted by kidneys
- INCREASE = increased intake, dehydration
- DECREASE = renal disease, GI loss, seasonal
How do reptiles metabolize potassium? What are common causes of increases and decreases?
cation present within cells —> ingested in the diet and excreted by kidneys
- INCREASE = increased intake, renal disease, urinary obstruction, redistribution into ECF (acidosis)
- DECREASE = reduced intake, increased GI or renal loss, redistribution into cells (redistribution syndrome)
What makes up total calcium? What causes artifactual changes? What is it regulated by?
iCa + protein bound Ca + chelated Ca
- sample analyzed
- storage time
- sample pH
PTH, calcitonin, calcitriol
What are some causes of iCa increases and decreases?
INCREASE = excessive Ca or vit D3 supplementation, osteolytic bone disease, primary hyperparathyroidism, pseudohyperparathyroidism, reproductively active female (laying egg shell)
DECREASE = insufficient dietary Ca or vit D3, inadequate UVB light, excessive dietary P, renal disease, hypoparathyroidism
What are phosphorus levels related to? What are some causes of increases and decreases?
Ca levels
- INCREASE = renal disease, nutritional secondary hyperparathyroidism, normal in young animals
- DECREASE = anorexia
What do creatinine levels indicate? What are 2 causes of increases?
skeletal and cardiac muscle condition
- traumatic venipuncture
- muscle pathology - capture myopathy (myoglobin produced by muscle breakdown causes renal disease)
What are 4 causes of hyperglycemia in reptiles? 4 causes of hypoglycemia?
HYPER = stress, elevated temperature, pancreatic neoplasia, DM
HYPO = anorexia, malnutrition, severe hepatic disease, septicemia
Why is it considerable difficult interpreting reptile radiographs?
- poor tissue contrast in coelom due to minimal visceral fat to provide contrast
- close anatomic proximity of internal organs
- no separation of body cavities
- image degradation due to skin, scales, and osteoderms
What are 2 purposes of providing orthogonal views of reptile radiographs?
- remove summation
- spacial location information
What kind of radiograph technique is preferred for reptiles?
horizontal beams
- lateral vertical beams alter confirmation of coelomic structures
- less manipulation of animal
Beam comparison:
- lateral, vertical beam - pulmonary tissue obscured by coelom
- lateral, horizontal beam - better view of pulmonary tissue
- lateral, horizontal beam with better restraining
How do respiratory interpretation of radiographs compare in reptiles?
mammal lung patterns are not applicable
- many reptile species themselves have anatomic variations
What are the best views for lizard radiographs? How are they positioned?
lateral and DV
pull legs out to minimize superimposition (may require sedation)
What are 3 unique structures of lizards to keep in mind when interpreting radiographs?
- coelom lacks diaphragm
- contain coelomic fat pads
- may or may not have a urinary bladder
Where is the heart located in lizard radiographs? What should be assessed for?
cranioventral coelom —> obscured by thoracic limbs, poor visualization on DV
- cardiomegaly
- tracheal position
What is being pointed to in these radiographs of a lizard?
heart
What is going on in this radiograph of a lizard?
soft tissue opacity cranial to a large heart, which is displacing the trachea dorsally
How do the lungs of lizards compare to mammals? What should be assessed for?
more radiolucent
- abscess/granuloma
- neoplasia
- pneumonia
What is the best view for interpreting the GIT of lizards? How does it typically move? What is the direction of how it runs?
DV —> anatomy depends on species
moves dynamically with the respiratory system
pylorus —> duodenum runs caudal —> cranial
What commonly causes prolonged GIT time?
decreased temperatures
What is labeled in this radiograph?
- red = heart
- green = liver
- purple = purple
- blue = gonad
- yellow = kidney
- orange = fat pad
What is outlined in this radiograph of a lizard?
female reproductive tract
How do pre-ovulatory ova look on radiographs?
spherical with a soft tissue opacity
(hemoclips seen in this radiograph, too)
How do post-ovulatory ova look on radiographs?
ovoid +/- visibly shelled
Where are the kidneys of lizards found? What should they be assessed for on radiographs?
dorsocaudal coelom
- renomegaly
- mineralization
What pathology is commonly associated with lizard urinary bladders (if they contain them)?
uroliths —> radiopaque; lamellar/concentric, irregular, rounded shape
- commonly found in bladder, colon, or cloaca
What is the reference for mineralization in lizards? What 5 things should be assessed for?
limbs compared to spine
- NSHP - decreased mineral density, fibrous proliferation, thinned cortices, long bone bowing, pathologic fx, periosteal reactions
- trauma - fx, joint subluxation, fibrous/mineralized callus can be seen within 8 weeks to 6 months; clinical healing precedes radiographic healing
- infection - lytic osteomyelitis, osteopathy
- gout - articular lysis
- soft tissue mineralization
Interpret findings in these radiographs.
- post-ovulatory ova seen
- poor bone density of distal limbs compared to spine
likely laying calcium into eggs, causing mobilization of calcium from bone —> negative energy balance = metabolic bone disease
Interpret findings in this radiograph.
- decreased mineral opacity of limbs
- kyphosis mid-spine to tail
Interpret findings in these radiographs.
- spinal kyphosis
- tail scoliosis
- periosteal reactions on long bones
What is osteitis deformans?
spinal osteopathy resulting in osteomyelitis and bone proliferation
What is the best view for radiographs in snakes? How should they be positioned?
lateral —> DV has superimposition of spine and ribs
sequential down the body (can straighten with a snake tube)
What is the snake heart like? What causes a normal increase in its density? What should be assessed for?
highly mobile and present at 20-35% snout to vent length (cranial in arboreal species; caudal in aquatic species)
post-prandial cardiac hypertrophy in boids
- cardiomegaly
- tracheal position
- displacement of ventral body wall
How many lungs to most snakes have? Where is it located?
most have 1 right lung and 1 vestigial left lung —> boids have both present
homogenous gas opacity typically starting at the cardiac silhouette at 25-60% SVT
How is the snake GIT visualized in radiographs? Where are the stomach, intestines, liver, and cloaca found?
poorly visualized and significantly affected by previous feeding
- STOMACH = 45-65% SVL (superimposed by liver)
- INTESTINES = 65-100% SVL
- LIVER = 30-60% SVL
- CLOACA = at last pair of ribs
Where are the gonads found in snakes? How do they compare in oviparous and viviparous species?
60-80% SVL
- OVIPAROUS = round to ovoid soft tissue structures, mineralized shells, retained eggs are more radiopaque
- VIVIPAROUS = fetal skeletons in late gestation
Where are the kidneys found in snakes? What should be assessed for?
70-95% SVL dorsal to the intestinal tract near the fat bodies
- gout
- renomegaly = displaced GIT and constipation
- masses
What is seen in this radiograph?
- mineralization of kidneys
- cloaca at last pair of ribs
What reference is used for proper musculoskeletal mineralization in snakes? What should be assessed for?
ribs compared to spine
- NSHP (rare, carnivores)
- fractures
- spondylitis, spondylosis
- spinal osteopathy
- osteomyelitis
- neoplasia
What are the best views used for radiographs of chelonians?
- ideally horizontal beam, REQUIRE 3 views
- CV, craniocaudal, lateral
What do lateral views of chelonian radiographs give the best view of?
dorsal lung field vs coelomic cavity
- cervical vertebrae going into lung field due to retraction of head into shell
What do craniocaudal views of chelonian radiographs give the best view of?
lung fields
- superimposition of pectoral girdle seen
What do DV views of chelonian radiographs give the best view of?
GIT
What musculoskeletal reference is used for mineralization in chelonians?
pectoral girdle
What is recommended for interpreting the cardiovascular system of chelonians?
echo or CT with contrast
- radiograph hard to read based on superimposition of pectoral girdle
How does the normal lung field of chelonians look like on radiographs? What can affect filling? What should be assessed for?
edicular (spongy) with muscular bands (ST opacity) and pulmonary vasculature; dorsally adheres to carapace
position of head and thoracic girdle
- abscess/granuloma
- neoplasia
- pneumonia (honeycomb ST opacity)
Chelonian, pneumonia:
- honeycomb pattern
- GI FB = gravel —> likely causing pulmonary pathology due to aspiration
What is the best view for interpreting the GIT of chelonians? Where is the stomach seen? What is commonly seen within it?
DV
left mid coelom
gravel —> can be normal, but may cause constipation, altered size of intestines, or gas opacities
What is commonly seen in female chelonian reproductive tracts?
visibly mineralized shelled eggs
What are 4 signs of dystocia in radiographs of chelonians?
- enlarged egg
- fractures shell
- eggs seen outside of season
- thicker shells = more opaque
can be retained in reproductive tract, urinary bladder, cloaca, or coelom (salpinx/oviduct rupture)
What are the 2 major aspects of the urinary system able to be seen in radiographs of chelonians? What pathology is commonly associated?
- KIDNEYS - dorsocaudal coelom
- URINARY BLADDER - species variation on # of lobes (increased in desert species for water retention)
UROLITHS - radiopaque, lamellar/concentric, commonly found in bladder or cloaca
How should the musculoskeletal system of chelonians be assessed?
- NSHP (metabolic bone disease)
- trauma - fracture, joint subluxation, callus (seen in shell within 12-18 months), persistent lucent defect possible
- osteomyelitis
- septic arthritis
- DJD
